Compositions stabilized with hydroxyphenyl acylamides

ABSTRACT

Hydroxypenyl acylamide compounds having the formula   ARE PREPARED BY REACTING AN ALKYL AMINOPHENOL WITH AN ACYL CHLORIDE. These compounds are useful as stabilizers of organic materials which are subject to oxidative deterioration.

United States Patent [1 1 Dexter et al.

[45] Dec. 24, 1974 1 COMPOSITIONS STABILIZED WITH HYDROXYPHENYLACYLAMIDES [75] Inventors: Martin Dexter, Briarcliff Manor;

Martin Knell, Ossining, both of NY.

[73] Assignee: Ciba-Geigy Corporation, Ardsley,

[22] Filed: Mar. 19, 1973 [21] Appl. No.: 342,335

Related US. Application Data [60] Division of Ser. No. 125,828, Marchi8, [971, Pat. No. 3,754,031, which is a continuation-in-part of Ser.No. 795,697, Jan. 3], 1969, abandoned.

[52] US. CL... 260/453 NC, 252/403, 260/4585 S,

3,542,573 ll/l970 Biland el al. 260/459 NC OTHER PUBLICATIONS A. N.Takahashi et 21]., Yakugaku Kcnkyu, Vol 36. pp. 149-162, 1965. GeigyAdvertisement, Modern Plastics Encyclopedia, Vol. 45, No. 14A, p. 476.Oct. 1968. Geigy Advertisement, Modern Plastics Encyclopedia, Vol.45,No. 1A, p. 398, Sept. 1967.

Primary Examiner-Melvyn l, Marquis Assistant Examiner-Gary R. Marshall[57] ABSTRACT Hydroxypenyl acylamide compounds having the formula areprepared by reacting an alkyl aminophenol with an acyl chloride. Thesecompounds are useful as stabilizers of organic materials which aresubject to oxidative deterioration.

5 Claims, N0 Drawings 1 COMPOSITIONS STABILIZED WITH HYDROXYPHENYLACYLAMIDES This is a division of application Ser. No. l25,828, filed onMar. l8, l97l, now U.S. Pat. No. 3,754,031. which in turn is acontinuation-in-part of Ser. No. 795,697, filed Jan. 3 l, 1969, nowabandoned.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to novelacylamide compounds. lt also relates to the use of these compounds asstabilizers of organic materials which are normally subject to oxidativeand/or thermal degradation.

The novel hydroxyphenyl acylamide antioxidant compounds ofthe presentinvention are represented by the formula R, and R are independentlylower alkyl groups having from l to 6 carbon atoms, and

n is a number from 2 to ID.

Illustrative examples of alkyl groups are methyl, ethyl, propyl,isopropyl, butyl. sec-butyl, tert-butyl, amyl, tert-amyl, hexyl and thelike. The branched alkyl groups have been found to be particularlyeffective and the most preferred groups are tert-alkyl, such as tbutyl,t-amyl. and the like. The acyl moiety of the novel antioxidant compoundsofthe present invention are derived from dicarboxylic acids containingfrom 4 to 12 carbon atoms. Illustrative dicarboxylic acids includesuccinic acid, glutaric acid. adipic acid, pimelic acid. suberic acid.azelaic acid and sebacic acid.

The phenyl acylamide compounds of the present invention are prepared byreacting an aminophenol and an acyl chloride. The reaction is carriedout in a solu tion containing the reacting materials. The usefulsolvents include ketones, hydrocarbons and aldehydes. lllustrativeexamples of such solvents are acetone. pyridine, dimethylformamide,methyl ethyl ketone, methyl isobutyl ketone. dioxane, and the like.

Stoichiometric amounts of the reactants are employed and a ratio of 1mole of acyl chloride to 4 moles of aminophenyl can be used; a moleration of 1:2 has been found to be particularly useful.

In the course of the reaction, hydrogen chloride is liberated formingthe amine hydrochloride and conse quently an alkaline material is usedto neutralize the hydrogen chloride. Suitable alkaline materials whichare used include, for example, sodium or potassium hydroxide, sodium orpotassium acetate, sodium or potassium carbonate, sodium or potassiumbicarbonate, and the like.

Illustrative examples of acyl chlorides which can be used are acidchlorides of adipic acid, succinic acid, sebacic acid, and the like.

In a typical reaction 1 mole of adipoyl chloride dissolved in acetone isadded to 0.5 mole of an alkyl aminophenol such as, for example,2,6-di-tert-butyl-4- aminophenol. An alkaline material, such as forexample, sodium hydroxide, is then added to the solution, accompanied byagitation. The desired product is washed, selectively recovered and thendried to obtain the desired hydroxyphenyl acylamide.

These compounds may be incorporated in the polymer substance during theusual processing operations, for example, by hot-milling, thecomposition then being extruded, pressed, roll-molded or the like intofilms. fibers, filaments, hollow-spheres and the likev The heatstabilizing properties of these compounds advaotw geously stabilize thepolymer against degradation during such processing at the hightemperatures generally encountered.

The stabilizers employed in this invention can also be used incombination with other stabilizersor additives. Especially usefulco-stabilizers are dilauryl-B-thiodipropionate anddistearyl-B-thiodipropionate.

The following formula represents CO S[;Jl\lll/Cl' which are in certaininstances very useful in combination with the stabilizers of thisinvention;

R-O-C- (C H l THZ S It R g H CH wherein R is an alkyl group having fromo to 24 carbon atoms; and n is an integer from I to o. The aboveeostabilizers are used in the amount of from lltll to I"? by weight ofthe organic material. and preferably from (H to 1%.

Other antioxidants. antiozonants, thermal stabilizers. ultraviolet lightabsorbers, coloring materials. tl \Ls. pigments, metal chelating agents.etc. may also be used in the compositions in combination with thestabili/ers of the invention.

The following examples will further illustrate the nature of the presentinvention without introducing any limitations thereto.

EX A MPLE l N,N 'bist 3,5-di-t-butyl-4h vd roxyphenyl ladipam ide 11.05g of 2,6-di-tert-hutyl-4-aminophenol (prepared by the proceduredescribed in US. Pat. No. 3.156.690) is dissolved in ml acetone and 4.57g adipoyl chloride in 10 ml acetone is added portionwise thereto. Thereaction is mildly exothermic and some solid material separates. Dilutesodium hydroxide (50 ml of lNl is added portionwise. accompanied byshaking. After the exothermic reaction is ended, 50 ml water is added tothe reaction mixture followed by cooling and the mix ture is thenfiltered. The solid material is washed twice with 50 ml portions of coldpetroleum ether to remove most of the red coloration and this isfollowed by drying. The weight ofthe product obtained is 8.87 g; melting point 269272. After recrystalization front etha nol, the desiredproduct is obtained in a yield of about 35%;21 melting point of 274-276dec.

Calculated Found Analysis:

EXAMPLE 2 N ,N '-bis( 3 ,5-di-t-butyl-4-hydroxyphenyl )sebaceamide Theprocedure of Example I was followed except that sebacoyl chloride wasemployed. The above named product was obtained which, afterrecrystallization from ethanol-water mixture, had a melting point of 21l2l3C.

Analysis: Calculated C. 74.96; H. 9.93; N. 4.60

Found C. 74.74; H, 987' N 436.

EXAMPLE 3 N.N '-bis( 3-methyl-4-hydroxy-54- hutylphenylladipamide Theprocedure of Example 1 was followed except that2-methyl-6-t-butyl-4-aminophenol was employed. The above named productwas obtained which, after recrystallization from ethanol-water mixture.had a melting point of 259260.5C.

mide

Following the procedure described in Example I, supra. except for theuse of 2-methyl-6-t-butyl-4- aminophenol (prepared by the proceduredescribed in US. Pat. No. 3,156,690) and sebacoyl acid chloride,N,N'-bis(3-rnethyl-5t-butyl-4'hydroxyphenyl)sebacamide is obtained.

Following the above described procedures. the fol lowing compounds arealso prepared:

N.N-bis(Z-methyl-S-t-butyl-4-hydroxyphenyl)suberamide.

N.N'-bis(3,5-di-isobutyl-4-hydroxyphenyl)pimelamide,

N,N '-bis( 3 .5-di-tert-hexylA-hydroxypbenylladipamide.

Since the oxidation of organic materials is slow at ambienttemperatures, even in the absence of antioxidants. the testing of theeffects of antioxidants must be conducted at elevated temperatures inorder to obtain results within a convenient time. The tests conducted onthe following material were made following oven aging in a forced draftoven, at a temperature of 300C.

EXAMPLE 5 Unstabilized polypropylene powder, (Hercules) Profax 650l wasthoroughly blended with 0.5% by weight ofN,N'-bis(3,5-dit-butyl-4-hydroxyphenyl)adipamide. The blended materialwas then milled on a tworoller mill at l82C, for it) minutes, afterwhich the stabilized polypropylene was sheeted from the mill and allowedto cool.

The polypropylene sheet was then cut into pieces and pressed for 7minutes on a hydraulic press at 218C and 2,000 pounds per square inchpressure. The resultant sheet of 25 mil thickness was tested forresistance to accelerated aging in a force draft oven at 300F.Unstabilized polypropylene specimen began to decompose within threehours. However, under the same condi tions. the polypropylene containingthe aforementioned antioxidant showed signs of decomposition only after205 hours.

Similar results are obtained when N,N'bis( 3 methyl5-t-butyl-4-hydroxyphenyl)sebacamide and N.N-bis(3,5-dimethyl4-hydroxyphenyl)adipamide are employed in place ofthecompound used in the above ex ample.

EXAMPLE 6 Stabilized rubber is prepared by mixing in the cold:

Parts ltltl ll 5 5.l| ill 15 Hevea latex crepe Steuric acid Zinc oxideDiphenylguamdine Sulfur adipamidc Hi The resultant mixture is vulcanizedat C and tested according to ASTM D-l206-52T. It was found that the timerequired to elongate a test strip from I20 mm to mm is considerablyshorter for the unstabilized rubber as compared with the stabilizedrubber.

Similarly. styrene-butadiene rubber as well as a blend of natural rubber(50 parts) and polybutadiene rubber (50 parts) are stabilized.

EXAMPLE 7 High impact polystyrene resin containing elastomer (i.e.,butadiene-styrene) is stabilized against loss of elongation propertiesby incorporation of 0.554 by weight ofN.N'-bis(3.5-di-t-butyl-4-hydroxyphenyl- )adipamide. Under the testconditions described below. the stabilized resin retains a higherpercentage of its original elongation properties. whereas theunstabilized resin retains less elongation properties.

The unstabilized resin is dissolved in chloroform and the stabilizerthen added. after which the mixture is cast on a glass plate and thesolvent evaporated to yield a uniform film which. upon drying, isremoved and cut up. and then pressed for 7 minutes at a temperature of163 and a pressure of 2,000 pounds per square inch into a sheet ofuniform thickness (25 mil). The sheets are then cut into strips.approximately 4 X 0.5 inches. a portion of these strips is then measuredfor length of elongation in the lnstron Tensile tester (lnstronEngineering Corporation. Quincy. Massachusetts). The remaining portionof the strips is aged in a forced draft oven for 6 weeks at 75C andthereafter tested for elongation.

Similar results are obtained with a terpolymer ofacrylonitrile-butadiene-styrene.

What is claimed is:

l. A composition of matter comprising polypropyl ene, natural rubber orbutadiene-styrene elastomer normally subject to oxidative deteriorationcontaining from 0.005 to 5% by weight of a hydroxyphenyl acylamidehaving the formula if 8 HO NH-C-C l'1 -CNH OH wherein R, and R areindependently alkyl groups containing up to 6 carbon atoms, and n is anumber from 2 to l0.

Zll

is additionally 0.0l to 29 by weight 0! polyolclin ll u stabilizerselected from dilauryl-B4hiodipropionntc anddistearyl-B-distezirylthiodipropionatc.

1. A COMPOSITION OF MATTER COMPRISSING POLYPROPYLENE, NATURAL RUBBER ORBUTADIEN -STYRENE ELASTOMER NORMALLY SUBJECT TO OXIDACTIVE DETERIORATIONCONTAINING FROM 0.005 TO 5% BY WEIGHT OF A HYDROXYPHENYL ACYLAMIDEHAVING THE FORMULA
 2. The composition of claim 1 wherein said acylamideis N,N''-bis(3,5-di-t-butyl-4-hydroxyphenyl)adipamide.
 3. Thecomposition of claim 1 wherein said acylamide isN,N''-bis(3,5-di-t-butyl-4-hydroxyphenyl)sebacamide.
 4. The compositionof claim 1 wherein said acylamide isN,N''-bis(3-methyl-4-hydroxy-5-t-butylphenyl)adipamide.
 5. A compositionof matter of claim 1 wherein there is additionally 0.01 to 2% by weightof polyolefin a co-stabilizer selected from dilauryl- Beta-thiodipropionate and distearyl-Beta -distearylthiodipropionate.